[SOLVED] transmitting a logic state over a long distance .

so all i need , is to transmit a logic or analog state over a very long distance . something around 4km to 5km . like a high state or a low state ... or a voltage value . all the possibilities use pre-defined protocols .
i want something from scratch . like it only transmits something very simple , like a voltage or a wave that i can later analyse

You did not said wired or wireless.

BillHo:
You did not said wired or wireless.

i cant even understand if this is a serious response or not , unless you think it’s practical to have a wire that is 4km long . unless i Hijack the telephone wire though .
of course it’s wireless dude .

Are both ends inside cellphone or wifi coverage?

There's lots of radio modules available that will go that kind of distance, without any cell or wifi.

amine2:
i cant even understand if this is a serious response or not , unless you think it’s practical to have a wire that is 4km long . unless i Hijack the telephone wire though .
of course it’s wireless dude .

So what wireless system are you going to use? Are the two points that are to be connected “line of sight”?

In the city, 4km is a long distance.

In the country, 4km might be the distance from your house to your water pump which supplies the house. A wired solution is probably appropriate for that.

4km is nearly 2.5 miles. Long way to run wires.
Good RF solution is needed.

“Superior outdoor LOS range of up to 28 miles”

More options

CrossRoads:
4km is nearly 2.5 miles. Long way to run wires.

Unless you need reliability.

CrossRoads:
900 MHz Long-Range RF Module | Digi International
"Superior outdoor LOS range of up to 28 miles"

More options
[url=http://[/url]]http://www.digi.com/products/xbee-rf-solutions][/color]http://www.digi.com/products/xbee-rf-solutions

You (still) have a problem with colour? :astonished:

i think the Xbee is too advanced for this .
let me phrase it like this . the only thing needed is a voltage .
l’ets say i have a lamp in the first position , if the lamp is on , then an other lamp 2.5miles away turns on almost in the same time , once the lamp in the first position turns off , the one 2.5miles away turns off …
all i need is a trigger signal .

(freaking forum, can't paste a simple link in without it screwing it up on me ...)

Well, unless you're going to install 2.5 miles of outdoor/direct burial rated wire, then RF is the choice.
Do you have clear line of sight from one location to the other? No trees, telephone poles, fences, weather, between the locations? Then a resilient RF solution with good antennas like the Digi stuff is the best answer.
If it is clear, like a mountain side overlooking a valley below, then other RF options may work, such as:

But the distance may not be enough; it may work if you slow the data rate down more.

Transmission distance(Open area): 520m (2Mbps)/750m(1Mbps)/1000m (250Kbps)

amine2:
i think the Xbee is too advanced for this .
let me phrase it like this . the only thing needed is a voltage .
l'ets say i have a lamp in the first position , if the lamp is on , then an other lamp 2.5miles away turns on almost in the same time , once the lamp in the first position turns off , the one 2.5miles away turns off ...
all i need is a trigger signal .

I don't see anything less that a Xbee working for you.
No matter how simple the information is, you still need to
cross the distance in a way that you would consider reliable.
Is the second light at a fixed location? Is there a phone connection
handy?
What options do you have?
Dwight

In the olden days 4 km was nothing for wire.
Sent data with current loops, 4-20ma, all the time

.

Yes, not much for wire, unless you have to buy a huge spool and install it.
And it's not cheap, hundreds of dollars for 5000' rolls, and that's just 1 conductor.

I'd be willing to give the $50 RF route a shot.

i think the Xbee is too advanced for this.

It takes advanced technology to transmit even 1 bit of information over that distance reliably, by wireless means.

i think the Xbee is too advanced for this .
let me phrase it like this . the only thing needed is a voltage .
l'ets say i have a lamp in the first position , if the lamp is on , then an other lamp 2.5miles away turns on almost in the same time , once the lamp in the first position turns off , the one 2.5miles away turns off ...
all i need is a trigger signal .

Well, sounds simple, just do it!

Without knowing anything about whats in between the transmitting end and the receiver its not possible to answer such a question.
The only guaranteed method would be 2 Arduinos with GPRS shields at both ends.
Any other solution might work, but its not possible to guarantee it will.

there are many buildings in the way .. and some high trees ..
the RF systems are meant to carry bytes of information . all i need is one bit .

there are many buildings in the way .. and some high trees ..
the RF systems are meant to carry bytes of information . all i need is one bit .

You need a reality check, one bit, or a million bits, the issues are pretty much the same. Kind of like saying you don't want a whole pizza delivered to the moon, you just want one slice delivered.

If you have mobile coverage at both locations then for a cheap usage (but not cheap to buy) option you could maybe just ring the other end and it detects the ring & caller ID but does not pickup the call. A short ring for on and a long ring for off. This could also be extended so the call is returned in the same manner so the original sender knows the call got through and the bit state is correct.
To prevent the SIM being cancelled you will probably need to use it periodically. Maybe send a text once per day/week listing the switching times so the base can compare.

EDIT:
Maybe not so expensive! This module breaks out the ring indicator pin.

thank you everyone , thank you Riva .
Zoomkat ← i want to build this from scratch … chips , antennas etc …
i know a guy that managed to send a FM radio signal from available parts … so i don’t think this would be impossible